Johnson, Lewis K., author
Allyn and Bacon, 1957
Buku Teks
Narver, John C., author
Holt, Rinehart and Winston, 1971
Buku Teks
Frank, Ronald E.
Richard D. Irwin , 1962
Buku Teks
Clark, Fred E.
MacMillan Co., 1931
Buku Teks
edited by Philip R. Cateora and Lee Richardson
Appleton-Century-Crofts, 1967
Buku Teks